Replace edge types with GrEdgeEffect.

src/gpu/effects/GrEdgeEffect.cpp

Index: src/gpu/effects/GrEdgeEffect.cpp
===================================================================
--- src/gpu/effects/GrEdgeEffect.cpp	(revision 0)
+++ src/gpu/effects/GrEdgeEffect.cpp	(revision 0)
@@ -0,0 +1,137 @@
+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "GrEdgeEffect.h"
+#include "gl/GrGLEffect.h"
+#include "gl/GrGLSL.h"
+#include "GrTBackendEffectFactory.h"
+
+class GrGLEdgeEffect : public GrGLEffect {
+public:
+    GrGLEdgeEffect(const GrBackendEffectFactory& factory, const GrDrawEffect&)
+    : INHERITED (factory) {}
+
+    virtual void emitCode(GrGLShaderBuilder* builder,
+                          const GrDrawEffect& drawEffect,
+                          EffectKey key,
+                          const char* outputColor,
+                          const char* inputColor,
+                          const TextureSamplerArray& samplers) SK_OVERRIDE {
+        const GrEdgeEffect& edgeEffect = drawEffect.castEffect<GrEdgeEffect>();
+        GrEdgeEffect::EdgeType type = edgeEffect.edgeType();
+
+        const char *vsName, *fsName;
+        const SkString* attrName =
+            builder->getEffectAttributeName(drawEffect.getVertexAttribIndices()[0]);
+        builder->fsCodeAppendf("\t\tfloat edgeAlpha;\n");
+
+        switch (type) {
+        case GrEdgeEffect::kHairLine_EdgeType:
+            builder->addVarying(kVec4f_GrSLType, "HairEdge", &vsName, &fsName);
+
+            builder->fsCodeAppendf("\t\tedgeAlpha = abs(dot(vec3(%s.xy,1), %s.xyz));\n",
+                                   builder->fragmentPosition(), fsName);
+            builder->fsCodeAppendf("\t\tedgeAlpha = max(1.0 - edgeAlpha, 0.0);\n");
+            break;
+        case GrEdgeEffect::kQuad_EdgeType:
+            GrAssert(builder->ctxInfo().caps()->shaderDerivativeSupport());
+            builder->addVarying(kVec4f_GrSLType, "QuadEdge", &vsName, &fsName);
+
+            // keep the derivative instructions outside the conditional
+            builder->fsCodeAppendf("\t\tvec2 duvdx = dFdx(%s.xy);\n", fsName);
+            builder->fsCodeAppendf("\t\tvec2 duvdy = dFdy(%s.xy);\n", fsName);
+            builder->fsCodeAppendf("\t\tif (%s.z > 0.0 && %s.w > 0.0) {\n", fsName, fsName);
+            // today we know z and w are in device space. We could use derivatives
+            builder->fsCodeAppendf("\t\t\tedgeAlpha = min(min(%s.z, %s.w) + 0.5, 1.0);\n", fsName,
+                                   fsName);
+            builder->fsCodeAppendf ("\t\t} else {\n");
+            builder->fsCodeAppendf("\t\t\tvec2 gF = vec2(2.0*%s.x*duvdx.x - duvdx.y,\n"
+                                   "\t\t\t               2.0*%s.x*duvdy.x - duvdy.y);\n",
+                                    fsName, fsName);
+            builder->fsCodeAppendf("\t\t\tedgeAlpha = (%s.x*%s.x - %s.y);\n", fsName, fsName, 
+                                   fsName);
+            builder->fsCodeAppendf("\t\t\tedgeAlpha = "
+                                   "clamp(0.5 - edgeAlpha / length(gF), 0.0, 1.0);\n\t\t}\n");
+            if (kES2_GrGLBinding == builder->ctxInfo().binding()) {
+                builder->fHeader.append("#extension GL_OES_standard_derivatives: enable\n");
+            }
+            break;
+        case GrEdgeEffect::kHairQuad_EdgeType:
+            GrAssert(builder->ctxInfo().caps()->shaderDerivativeSupport());
+            builder->addVarying(kVec4f_GrSLType, "HairQuadEdge", &vsName, &fsName);
+
+            builder->fsCodeAppendf("\t\tvec2 duvdx = dFdx(%s.xy);\n", fsName);
+            builder->fsCodeAppendf("\t\tvec2 duvdy = dFdy(%s.xy);\n", fsName);
+            builder->fsCodeAppendf("\t\tvec2 gF = vec2(2.0*%s.x*duvdx.x - duvdx.y,\n"
+                                   "\t\t               2.0*%s.x*duvdy.x - duvdy.y);\n",
+                                   fsName, fsName);
+            builder->fsCodeAppendf("\t\tedgeAlpha = (%s.x*%s.x - %s.y);\n", fsName, fsName,
+                                   fsName);
+            builder->fsCodeAppend("\t\tedgeAlpha = sqrt(edgeAlpha*edgeAlpha / dot(gF, gF));\n");
+            builder->fsCodeAppend("\t\tedgeAlpha = max(1.0 - edgeAlpha, 0.0);\n");
+            if (kES2_GrGLBinding == builder->ctxInfo().binding()) {
+                builder->fHeader.append("#extension GL_OES_standard_derivatives: enable\n");
+            }
+            break;
+        };
+
+        SkString modulate;
+        GrGLSLModulate4f(&modulate, inputColor, "edgeAlpha");
+        builder->fsCodeAppendf("\t%s = %s;\n", outputColor, modulate.c_str());
+
+        builder->vsCodeAppendf("\t%s = %s;\n", vsName, attrName->c_str());
+    }
+
+    static inline EffectKey GenKey(const GrDrawEffect& drawEffect, const GrGLCaps&) {
+        const GrEdgeEffect& QuadEffect = drawEffect.castEffect<GrEdgeEffect>();
+
+        return QuadEffect.edgeType();
+    }
+
+    virtual void setData(const GrGLUniformManager&, const GrDrawEffect&) SK_OVERRIDE {
+    }
+
+private:
+    typedef GrGLEffect INHERITED;
+};
+
+///////////////////////////////////////////////////////////////////////////////
+
+GrEdgeEffect::GrEdgeEffect(EdgeType edgeType) : GrEffect() {
+    if (edgeType == kQuad_EdgeType) {
+        this->addVertexAttrib(kVec4f_GrSLType);
+    } else {

[robertphillips, 2013/03/26 14:09:20]

convert the "someday" comment into a "TODO"?

[bsalomon, 2013/03/26 14:45:30]

Done.

+        this->addVertexAttrib(kVec4f_GrSLType);  // someday this will matter
+    }
+    fEdgeType = edgeType;
+}
+
+void GrEdgeEffect::getConstantColorComponents(GrColor* color, uint32_t* validFlags) const {
+    *validFlags = 0;
+}
+
+const GrBackendEffectFactory& GrEdgeEffect::getFactory() const {
+    return GrTBackendEffectFactory<GrEdgeEffect>::getInstance();
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+GR_DEFINE_EFFECT_TEST(GrEdgeEffect);
+
+GrEffectRef* GrEdgeEffect::TestCreate(SkMWCRandom* random,
+                                      GrContext*,
+                                      const GrDrawTargetCaps& caps,
+                                      GrTexture*[]) {
+    // Only kHairLine works without derivative instructions.
+    EdgeType edgeType;
+    if (caps.shaderDerivativeSupport()) {
+        edgeType = static_cast<EdgeType>(random->nextULessThan(kEdgeTypeCount));
+    } else {
+        edgeType = kHairLine_EdgeType;
+    }
+    return GrEdgeEffect::Create(edgeType);
+}